I think I can use tin foil, a HID brain and some fancy algorithms to decode an EKG from a person. I'm fuzzy on the details here, I might need some extra electronics. The HID brain is a usb device and so supplies 5V DC power. The current can go up to 500 mA. Therefor is it's connected to my laptop, even if the laptop is plugged into a 220V outlet, the testee isn't going to get electrocuted, right?